Generally, a wind turbine includes a tower, a nacelle mounted on the tower, and a rotor coupled to the nacelle. The rotor typically includes a rotatable hub and a plurality of rotor blades coupled to and extending outwardly from the hub. Each rotor blade may be spaced about the hub so as to facilitate rotating the rotor to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy.
Proper lubrication of the various open gears in wind turbines has proven to be an important consideration in the operation and maintenance of the systems. This is especially true for the pitch control gears associated with each of the turbine blades. These gears operate in a relatively small defined positional range during the majority of the wind turbine's operating life wherein the pitch of the rotor blades is maintained relatively constant at the maximum design power operation of the wind turbine. At this position, the pitch of the blades is generally maintained between 0° and 3° (known as the 0° position) with or without automatic load control. The engaged pitch drive gears in this localized area are subjected to relatively high loads induced in large part by the torsional forces acting on the blades. The remaining gear teeth are only infrequently loaded, for example when the blades are feathered from the 0° position for power reduction or load control.
The grease that is applied to the gear teeth in the 0° position of the pitch drives is displaced from the contact areas long before the remaining circumferential sectors of the gears. Frictional corrosion can occur in this area without frequent and regular lubrication. Unfortunately, the engaged teeth between the driving pinion gear and the ring gear are difficult to access for greasing as long as the pitch drive remains in an operational position. Typically, the blades must be moved into a “lubricating” position during a maintenance procedure to adequately lubricate the engaged teeth at the 0° position.
Accordingly, a simple and reliable system that allows for adequate lubrication of the 0° pitch drive gears without shutdown of the wind turbine would be useful in the industry.